The technique currently applied for the production of sintered, vulcanized or pressed articles or products varies according to the mixture and the characteristics of the substance or material used for the production, and particularly depends on the handling necessary for the processing of this mixture into finished products of the quality desired. Under these circumstances the technique suitable for the manufacture of a single product or article demands various or different methods of production. This means that a very large number of specific machines, devices and tools is necessary which must be developed in order to meet the specific technical requirements for the manufacture of each article or product. To illustrate the relevant aspect of the technique, here is a short description of the main phases common to the production of a large number of finished products. These may be defined by the following general stages:
preparation of the mixture,
processing of the mixture into a finished product, especially by pressing or compressing and handling.
completion of the above mentioned products.
The preparation of the mixed raw materials for the manufacture of non-metallic products consists of a chemical and mechanical conditioning of the material component, the proportions and mixture of which, with possible filling material, leads to a homogeneous mass of a high consistency. Subsequently the mixture can be transferred to the desired form which however must be such that the progress of the stipulated chemical reaction is guaranteed depending on the temperature and the pressure applied. The preparative phase of the mixture only requires a comparatively small investment, as it can be realized with simple equipment. However, the preparation of this mixture has to be done with utmost care and attention so that the finished products or articles will be of a suitable quality.
The process of metallic material means in most cases that their forms must be changed, brought about by the forming, drawing, pressing and so on, of metallic alloys supplied by a distributor with the help of conventional presses adapted to the articles to be produced. The stage at which the mixture is processed into finished products or articles plays a dominant role in the entire technological process. However, the construction of the equipment used for the processing of this this mixture. In most cases the manufacturing process is distributed among various workships each of which is responsible for an exactly defined phase of the technological process. In order to increase the production capacity it is therefore necessary to acquire a large number of expensive machines and to employ a large number of qualified workers. What is more, the space requirement of the numerous machines increases the costs of the infra-structure and thus the general costs of investment.
The equipment or installations for a continuous and automated production of certain asbestos products, for instance, for the production of cardboard or asbestos paper, incorporate an installation similar to a paper machine specifically adapted to asbestos. A paper machine working with a speed of more than 600 meters/min. for the production of normal paper proves to be somewhat inefficient for the production of asbestos paper, because in this case it has to work with a speed of between a maximum of 23 to 40 meters/min. The running of such a machine shows even more disadvantages concerning mainly the costs, energy consumption and the large consumption of water which has to be drained and evaporated.
The production of asbestos cement products up to now has been realized by space consuming and expensive machines. The process applied for the production of tubes requires much space and specific equipment on account of their length. What is more, the mixture must be put on cylinders of the desired diameter and desired length which have to be removed mechanically after the drying process.
Thermoplastic synthetics which are chemically stabilized and enriched with auxiliary components and which are available in the form of a mixture which can be molded when warm, can easily be converted into finished products in a continuous process by extruders, syringes, calandering or cylinders. These mixtures consisting of synthetics as well as those formed of thermosetting plastics can also be produced by means of pressing, but with less productivity. However, the use of presses cannot be avoided where stiff mixtures are to be converted or formed.
The products consisting of natural rubber or of synthetic rubber are very numerous and manifold regarding their form and composition.
The technological process for the conversion of these mixtures containing synthetic or natural rubber used in particular for the production of tires is very complex.
The current state of the technique may be summarized as follows:
The attributes and characteristics of the specific material, mixtures and alloys determine the choice of the conversion process whereas the forms and characteristics of the finished products determine the choice of handling. The conversion method and the handling which are applied during the conversion represent the technological process and determine the choice of the machines and the equipment suitable for each specific case.